Update the Juvix lock file when the Package file changes

[paulcadman]

Adds a new version of the lock file that stores the hash (sha256 digest) of the package file (Package.juvix, juvix.yaml) it was generated from as a field:

# This file was autogenerated by Juvix version 0.5.4.
# Do not edit this file manually.

version: 2
checksum: d05940a4d3dc0e15451d02e1294819c875ba486ee54e26865ba8d190ac7c27c3
dependencies:
- git:
    name: stdlib
    ref: f68b0614ad695eaa13ead42f3466e0a78219f826
    url: https://github.com/anoma/juvix-stdlib.git
  dependencies: []

The lock file is regenerated when the hash of the package file doesn't match the value of the checksum field, i.e when the user updates the package file.

Existing lock files are automatically migrated to version 2.

• Closes Automatically update the lock file when the project dependencies and lock file are not in sync #2464

[jonaprieto]

LGTM